COMET ASSAY STUDIES INDICATE THAT CAFFEINE-MEDIATED INCREASE IN RADIATION RISK OF EMBRYOS IS DUE TO INHIBITION OF DNA-REPAIR

It is well known that under specific conditions caffeine is able to en hance radiation risk of mammalian cells by a factor of similar to 1.5- 2. Various mechanisms are discussed in the literature as possible expl anations for this interaction, Inhibition of DNA repair plays a crucia l role in the discussion, although direct evidence for this assumption is difficult to obtain, We used the 'comet assay' in order to analyse the significance of repair inhibition by caffeine in the two-cell sta ge of mammalian gestation, Our data show that at the concentration nec essary for increasing radiation risk (2 mM), caffeine effectively inhi bits the restitution of radiation-damaged DNA.